According to regulations ...

A ticket collector of the french railway company SNCF demanded to a passenger to pay a fee of 5,10€ because he was travelling with a box full of ... snails. The collector explained that like for a cat, a bird or a dog this is regulation that any pet of less than 6 kg travelling in a bag has to pay this fee. For any bigger animal, you need to pay a half-price ticket. That puts the dozen of oysters at ... 120,-€ .